Off-the-shelf Cassandra has a fair amount of flexibility in its architecture. Open Source Cassandra is the thing that is in the front end. And the team is excited about the idea of collaborating with the development community around some of the generally useful abstractions needed to build this managed database experience. More at https://aws.amazon.com/blogs/opensource/contributing-cassand...
Amazon, Microsoft, Google, Oracle, IBM and others are all major contributors to open-source software.
"Amazon EMR has been adding Spark runtime improvements since EMR 5.24, and discussed them in Optimizing Spark Performance. EMR 5.28 features several new improvements."
Have these improvements been contributed back to Spark? When I take a look at the improvements themselves, it looks like all Amazon did was upgrade Spark from 2.3 to 2.4.
The page I linked lists plenty of projects if you're looking for actual OSS work.
Again this seems like a random example. What is so important about this particular change over all the other open-source contributions?
The improvements they're claiming is for their own EMR product, not to Spark, and they do make updates to software to run better on their own own infrastructure. That's what their customers care about.
You seem dedicated to believing that Amazon has done nothing for open-source even I pointed you to an exhaustive list of their contributions. At this point, there's nothing more to say.
Here are some examples from my team’s 2019 work: We contributed numerous changes to containerd. We open sourced firecracker-containerd, and we also created a Go SDK that others are using to work with Firecracker. We contributed to Debian and the Debian kernel team. We contributed to Envoy. We collaborated with a number of communities, including Kata Containers, Red Hat’s Clair, and the Open Container Initiative. All of these examples are sustained investments, not one offs.